Preserving channel strain in fin cuts

ABSTRACT

A method of forming a semiconductor structure includes forming a fin cut mask over a region in a fin field-effect transistor (finFET) structure. The finFET structure includes one or more fins and one or more gates and source/drain regions formed over the one or more fins in active regions of the finFET structure. The method also includes performing a fin cut by removing a portion of at least one fin. The portion of the at least one fin is determined by an exposed area of the fin cut mask. The exposed area of the fin cut mask includes at least a portion of the at least one fin between a first dummy gate and a second dummy gate formed over the at least one fin. The method further includes removing the fin cut mask and depositing an oxide to replace the portion of the at least one fin removed during the fin cut.

BACKGROUND

The present application relates to semiconductors, and morespecifically, to techniques for forming semiconductor structures.Various types of field-effect transistor (FET) devices may be used insemiconductor structures, integrated circuits and other electronicdevices. Fin FETs (FinFETs) are a type of FET device, where fins arepatterned on a substrate.

SUMMARY

Embodiments of the invention provide techniques for preserving channelstrain in fin cuts.

For example, in one embodiment a method of forming a semiconductorstructure comprises forming a fin cut mask over a region in a finFETstructure. The finFET structure comprises one or more fins and one ormore gates and source/drain regions formed over the one or more fins inactive regions of the finFET structure. The method also comprisesperforming a fin cut by removing a portion of at least one of the fins.The portion of said at least one fin is determined by an exposed area ofthe fin cut mask. The exposed area of the fin cut mask comprises atleast a portion of said at least one fin between a first dummy gate anda second dummy gate formed over said at least one fin. The methodfurther comprises removing the fin cut mask and depositing an oxide toreplace the portion of said at least one fin removed during the fin cut.

In another embodiment, a semiconductor structure comprises a finFETstructure, at least one fin cut and an oxide layer. The finFET structurecomprises one or more fins and one or more gates and source/drainregions formed over the one or more fins in active regions of the finFETstructure. Said at least one fin cut is between a first gate structureand a second gate structure formed over at least one of the fins. Theoxide layer is formed between adjacent portions of said at least one finbetween the first gate structure and the second gate structure. Thefirst gate structure comprises a first dummy gate formed over said atleast one fin and a first gate patterning mask formed over the firstdummy gate. The second gate structure comprises a second dummy gateformed over said at least one fin and a second gate patterning hard maskformed over the second dummy gate. Spacers are formed on sidewalls ofthe first gate structure and the second gate structure.

In another embodiment, a semiconductor structure comprises a finFETstructure, at least one fin cut and an oxide layer. The finFET structurecomprises one or more fins and one or more gates and source/drainregions formed over the one or more fins in active regions of the finFETstructure. Said least one fin cut is between a first gate structure anda second gate structure formed over at least one of the fins. The oxidelayer is formed between adjacent portions of said at least one finbetween a pair of spacers, a first one of the pair of spacers being partof a first gate structure and a second one of the pair of spacers beingpart of a second gate structure. The first gate structure comprises atleast a portion of a first gate patterning hard mask formed over a firstdummy gate, the first dummy gate being removed when performing the fincut. The second gate structure comprises at least a portion of a secondgate patterning hard mask formed over a second dummy gate, the seconddummy gate being removed when performing the fin cut.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a top-down view of a semiconductor structure, accordingto an embodiment of the invention.

FIG. 2 depicts a top-down view of an active area of the FIG. 1semiconductor structure, according to an embodiment of the invention.

FIG. 3 depicts a side-cross sectional view of a semiconductor structure,according to an embodiment of the present invention.

FIG. 4 depicts a side cross-sectional view of the FIG. 3 semiconductorstructure with a fin cut mask, according to an embodiment of the presentinvention.

FIG. 5 depicts a side cross-sectional view of the FIG. 3 semiconductorstructure with another fin cut mask, according to an embodiment of thepresent invention.

FIG. 6 depicts a side cross-sectional view of the FIG. 3 semiconductorstructure with another fin cut mask, according to an embodiment of thepresent invention.

FIG. 7 depicts a side cross-sectional view of the FIG. 4 structurefollowing a dry etch, according to an embodiment of the presentinvention.

FIG. 8 depicts a side cross-sectional view of the FIG. 7 structurefollowing a nitride and silicon etch, according to an embodiment of thepresent invention.

FIG. 9 depicts a side cross-sectional view of the FIG. 8 structurefollowing removal of the fin cut mask and deposition of an oxide,according to an embodiment of the present invention.

FIG. 10 depicts a side cross-sectional view of the FIG. 7 structurefollowing a nitride open, according to an embodiment of the presentinvention.

FIG. 11 depicts a side cross-sectional view of the FIG. 10 structurefollowing a polysilicon pull and nitride etch, according to anembodiment of the present invention.

FIG. 12 depicts a side cross-sectional view of the FIG. 11 structurefollowing a silicon etch, according to an embodiment of the presentinvention.

FIG. 13 depicts a side cross-sectional view of the FIG. 12 structurefollowing removal of the fin cut mask and deposition of an oxide,according to an embodiment of the present invention.

FIG. 14 depicts a side cross-sectional view of the FIG. 12 structurefollowing removal of the remaining gate patterning hard mask andspacers, according to an embodiment of the present invention.

FIG. 15 depicts a side cross-sectional view of the FIG. 14 structure,following removal of the fin cut mask and deposition of an oxide,according to an embodiment of the present invention.

FIG. 16 depicts a plot and semiconductor structure illustrating channelstrain preservation, according to an embodiment of the presentinvention.

DETAILED DESCRIPTION

Illustrative embodiments of the invention may be described herein in thecontext of illustrative methods for preserving channel strain in fincuts, along with illustrative apparatus, systems and devices having fincuts formed using such methods. However, it is to be understood thatembodiments of the invention are not limited to the illustrativemethods, apparatus, systems and devices but instead are more broadlyapplicable to other suitable methods, apparatus, systems and devices.

In three-dimensional (3D) semiconductor structures such as semiconductorstructure with fins, the fins are initial formed with high strain. Whenthe fins in such structure are cut to form devices such as finfield-effect transistors (FinFETs), there is a loss in strain. Theearlier the fins are cut, the greater the loss in strain. Thus, it wouldbe desirable in methods for forming fin structures to cut fins later inthe process. For example, performing the fin cut after gate andepitaxial source/drain formation can reduce the fin length dependentstrain loss observed when cutting the fins. Advantageously, preservingor retaining channel strain preserves carrier mobility and the oncurrent, I_(on), realizing various performance benefits. For example,preserving the channel strain can results in 1-10% increases in thedrive current with no additional leakage current in some embodiments.

Performing channel or fin cuts later in the formation of a semiconductorstructure allows for minimizing or reducing spacer etching or pulldownduring CT reactive-ion etching (RIE). CT refers to a sequence ofprocessing steps involving deposition, lithography, and dry and wetetches where a dummy gate is patterned into its final dimension. Gatecorners are more susceptible to damage and erosion, which can lead toepitaxial nodule growth on exposed dummy gates, which may be formed ofamorphous silicon (a-Si). Performing channel or fin cutes later in aprocess also helps to prevent shorting of the gate-CA/TS due to morerobust spacers downstream in contact formation during self-alignedcontact etching. CA/TS refers to a sequence of steps where a metal thinfilm is inserted between gates to contact source/drain epitaxial films.When this is done, care should be taken to avoid contact of the metalthin film to the gate material, as such contact can cause an electricalshort.

Performing channel or fin cuts later in processing or formation of asemiconductor structure also enables a single diffusion break at tighterground rules. This can be advantageous, for example, in fin cuts throughthe gate and dielectric fill for structures using a single diffusionbreak (SDB). When using a SDB, the length of the fin cut is very small,such as less than 30 nm in some embodiments. Advantageously, use of SDBenables better control for fin cuts in short lengths of the fin sincethe process can be self-aligned to the gates.

Also, embodiments can provide for reducing the end capacitance of asemiconductor structure by performing channel or fin cuts later in theprocessing or formation of the structure. Compared with earlier fincuts, embodiments provide for longer fin length, such as fin length thatis longer by ½ the gate width and spacer thickness. As additionalfeatures, embodiments enable only one side of a spacer to be preserved,can completely remove gate wrapping around a fin, and/or can at leastpartially preserve materials that are used for gate patterning after fincuts.

FIG. 1 shows a top-down view 100 of a semiconductor structure. As shown,the semiconductor structure includes a negative field-effect transistor(NFET) region 102 and a positive field-effect transistor (PFET) region104. The semiconductor structure shown in FIG. 1 includes four activearea masks 106-1, 106-2, 106-3 and 106-4 collectively referred to hereinas active area masks 106. The active area masks 106, as their nameindicates, are masks that define active areas of a structure. Each ofthe active areas may comprise one or more multiple fins. The fins may becontained in the active areas defined by active area masks 106, but arenot shown in FIG. 1 for clarity. Fins contained in the active areas canbe 10-10,000 nm in length as measured in direction A-A and may be 6-100nm in width as measured in direction B-B in some embodiments. The activeareas 106 may be formed of silicon (Si), silicon germanium (SiGe),gallium arsenide (GaAs) or various other semiconducting materials.Although FIG. 1 shows an example where each of the active area masks 106is the same size, this is not a requirement. Two or more differentactive area masks in a semiconductor structure may have differentlengths, widths and/or heights.

As shown, there are two active area masks 106-1 and 160-2 in the NFETregion 102 and two active area masks 106-3 and 160-4 in the PFET region104. The particular number of active area masks 106 may be selected asdesired for a particular application, and embodiments are not limited tothe specific example shown in FIG. 1. For example, more or fewer thanfour active area masks may be used, as well as more or fewer than twoactive area masks in NFET and PFET regions of a structure. Also, whileFIG. 1 shows an example wherein there are the same number of active areamasks in each of the NFET and PFET regions, this is not a requirement.

The FIG. 1 structure also shows a number of gate cut masks 108-1, 108-2,108-3 and 108-4, collectively referred to herein as gate cut masks 108.The gate cut masks 108 may be lithography layers used to define theregion of the gates that will be cut. Once the gate cut masks 108 areused and the appropriate process sequence followed, the gates will nolonger be continuous across multiple active area masks 106.

In some embodiments, the gate cut masks 108 may have a length, measuredin direction A-A, in the range of 20-2000 nm. The gate cut masks 108 mayhave a width, measured in direction B-B, in the range of 10-100 nm insome embodiments. Each of the gate cut masks 108 in FIG. 1 is shown asbeing equal in size, but this is not a requirement and in otherembodiments different ones of the gate cut masks 108 may have differentlengths, widths and/or heights.

The FIG. 1 structure includes a number of contacts 110-1, 110-2, 110-3,110-4, 110-5 and 110-6, collectively referred to herein as contacts 110.The contacts 110 may be formed of varying materials, such tungsten (W),tungsten alloys, copper (Cu), cobalt (Co), etc. in some embodiments.Different ones of the contacts 110 are shown with different shading toindicate that they are formed using multiple lithography steps. Forexample, contacts 110-1, 110-2, 110-5 and 110-6 may be formed in onelithography step while contacts 110-2 and 110-4 may be formed in anotherlithography step.

As shown, certain of the contacts 110 are formed such that they spanonly a single one of the active areas masks 106. For example, contacts110-1, 110-5 and 110-6 are formed in each of the active area masks 106but do not span any two of the active area masks 106. Other contacts,however, may span multiple active area masks. Contacts 110-2, 110-3 and110-4 are shown as not spanning active area masks 106-1 and 106-2, butdo span and connect active area masks 106-3 and 106-4 as shown. Moregenerally, different ones of the contacts 110 may span one or moremultiple fins. Each contact 110 may have a length, measured in directionB-B, that depends on the width of the active area mask 106 that itcontacts as well as depending on the number of active area masks 106which that contact spans. Each contact 110 may have a width, measured indirection A-A, in the range of 10-2000 nm in some embodiments. Althoughnot explicitly shown in FIG. 1, source/drain regions are formedunderneath the contacts 110.

Each of the contacts 110 in FIG. 1 is shown as having the same width andheight, but this is not a requirement and in other embodiments differentones of the contacts may have different widths and/or heights inaddition to having different lengths as described.

The FIG. 1 structure also includes a number of gates 112-1, 112-2,112-3, 112-4, 112-5, 112-6, 112-7 and 112-8 collectively referred toherein as gates 112. The gates 112 may be formed of polycrystalline Si,a-Si, amorphous Carbon (C), etc. in some embodiments. Each of the gates112, before fin cuts, may have a length, measured in direction B-B, inthe range of 10-10000 nm in some embodiments, which is based on theoverall size of the FIG. 1 structure. Each of the gates 112 may have awidth, measured in direction A-A, in the range of 5-500 nm in someembodiments. Each of the gates 112 may have a height, measured in thetop-down direction of FIG. 1, in the range of 10-500 nm in someembodiments. Although shown in FIG. 1 as being equal in size, differentones of the gates 112 may be of different sizes relative to one anotherin terms of length, width and/or height as desired.

FIG. 1 shows, in a dashed outline box, a sample active region 150. FIG.2 shows a close-up top-down view of the active region 150. The activeregion 150 has a width, in direction A-A of FIG. 1, spanning between andincluding portions of contacts 110-5 and 110-6. The active region 150has a fin cut width that spans between the centers of adjacent gates112-7 and 112-8. The fin cut width, as will be described in furtherdetail below with respect to FIGS. 4-6, is not required to span betweencenters of adjacent ones of the gates 112.

FIGS. 3-13 below depict side cross-sectional views of an active regionof a semiconductor structure, and detail sample processes for formingfin cuts in such structures. The cross-sectional views shown in FIGS.3-13 are taken in a direction C-C shown in FIG. 2 for active region 150,although the structures shown in FIGS. 3-13 are shown before formationof contacts and do not use the same reference numerals as FIGS. 1 and 2for clarity of illustration.

FIG. 3 depicts a side cross-sectional view 300 of an active region of asemiconductor structure 300 after flowable chemical vapor deposition(FVCD). The FIG. 3 structure includes a substrate 302, source/drainregions 304, dummy gates 306, sacrificial layers 308 and 310 formed overthe gates 306, spacers 312 surrounding the dummy gates 306 andsacrificial layers 308 and 310, a poly open CMP layer 314 surroundingspacers 312 and formed over source/drain regions 304, and oxide 316between the poly open CMP layer 314. To form the FIG. 3 structure, thesubstrate 302 or fin is first formed, followed by formation of the dummygates 306 and source/drain epitaxy.

The substrate 302 is a fin structure, and may be formed of Si, SiGe orGaAs in some embodiments. Source/drain epitaxial layers 304 are formedover the substrate 302 between the dummy gates 306. Source/drainepitaxial layers 304 may be formed of Si, SiGe, germanium (Ge), GaAs orsilicon phosphide (SiP) in some embodiments. Source/drain epitaxiallayers 304 may have widths in the range of 10-1000 nm and heights in therange of 10-100 nm in some embodiments.

Dummy gates 306 may be formed of silicon, polysilicon, a-Si or C in someembodiments. Dummy gates 306 may have widths in the range of 10-500 nmand heights in the range of 10-200 nm in some embodiments. Sacrificiallayers 308 and 310 provide a gate patterning hard mask. Sacrificiallayer 308 may be an oxide with sacrificial layer 310 being a nitride, orvice versa. Although sacrificial layer 308 is shown having a smallerheight than sacrificial layer 310 in FIG. 3, this is not a requirement.The relative heights of sacrificial layers 308 and 310 may vary asdesired, with their total height being in the range of 2-50 nm in someembodiments.

Spacers 312 may be nitride spacers in some embodiments, although othersuitable materials may be used in other embodiments. The spacers 312 mayhave a thickness in the range of 2-20 nm in some embodiments. Poly openCMP layer 314 surrounds the spacers 312 and the tops and sides ofsource/drain epitaxial layers 304 that extend above the top of thesubstrate 302. Poly open CMP layer 314 may be formed of nitride oranother dielectric film that is sufficiently different in propertiesfrom oxide such that it may be removed selective to oxide. Poly open CMPlayer 314 may have a thickness in the range of 2-50 nm in someembodiments. The poly open CMP layer 314 is an optional layer, which maybe excluded in some embodiments such that there is one less film to etchbefore exposing the underlying epitaxial film.

FIGS. 4-6 show the FIG. 3 structure following formation of fin cut masks402, 502 and 602, respectively. The fin cut masks 402, 502 and 602 maybe photoresists or other patterning layers including but not limited toan organic polymer layer (OPL), a Silicon-Containing Anti-ReflectiveCoating (SiARC), a Titanium-Containing Anti-Reflective Coating (TiARC),other hard mask materials, etc. that are patterned as shown in FIGS.4-6, respectively. The openings in fin cut masks 402, 502 and 602 mayspan from 10-10,000 nm in some embodiments.

FIG. 4 shows a side cross-sectional view 400 of the FIG. 3 structurefollowing formation of fin cut mask 402 that exposes approximately halfof the gate masks for dummy gates 306, and corresponds to the fin cutmask illustrated in active region 150 shown in FIGS. 1 and 2. FIG. 5shows a side cross-sectional view 500 of the FIG. 3 structure followingformation of fin cut mask 502 that exposes none of the gate masks fordummy gates 306, such that only the oxide 316 between the dummy gates306 is exposed. FIG. 6 shows a side cross-sectional view 600 of the FIG.3 structure following formation of fin cut mask 602 that exposes all ofthe gate masks for dummy gates 306.

FIGS. 4-6 show three possible options for forming a fin cut mask.Embodiments, however, are not limited to the specific examples shown inFIG. 4-6. Fin cut masks may vary between exposing all or none of thegate masks as desired for a particular application. FIGS. 7-13 showprocessing steps performed after forming the fin cut mask 402 shown inFIG. 4, but similar steps may be used with other fin cut masks as willbe detailed below.

FIG. 7 shows a side cross-sectional view 700 of the FIG. 4 structurefollowing a buffered oxide (BHF) etch, which etches the oxide 316exposed by fin cut mask 402. The BHF etch may use a mixture ofhydrofluoric acid (HF) and a buffering agent such as ammonium fluoride(NH₄F). BHF is used in a wet etch process, but dry etches may be also beused in some embodiments. In this particular example, the BHF etch maybe 150 nm to expose the poly open CMP 314 on the source/drain epitaxiallayer 304 formed between the dummy gates 306.

FIGS. 8-10 show a first process, whereby the fin length is longer byhalf the width of the fin cut mask 402 and the spacer 312 thickness ascompared to an early fin cut.

FIG. 8 shows a side cross-sectional view 800 of the FIG. 7 structurefollowing nitride and silicon etches. The nitride etch removes the polyopen CMP 314 on the top of the source/drain epitaxial layer 304 betweendummy gates 306. This nitride etch, as shown, will also form notches inthe gate hard mask, spacer 312 and poly open CMP layer 314 on the sidesof the dummy gates 306. The nitride etch may be substantiallydirectional, such that the poly open CMP layer 314 on the sidewalls ofthe spacers 312 surrounding dummy gates 306 remains mostly intact asshown. The nitride etch may comprise a dry etch such as RIE in someembodiments.

Following the nitride etch, a silicon etch is used to remove thesource/drain epitaxial layer 304 between dummy gates 306 as well as toform the fin cut in substrate 302. The silicon etch may utilize the samedry etch or ME used to remove the poly open CMP layer 314. If differentetch chemistries are required to remove the poly open CMP layer 314 andthe source/drain epitaxial layer, they may be applied in an appropriatesequence so as to remove the materials as illustrated.

FIG. 9 shows a side-cross-sectional view 900 of the FIG. 8 structurefollowing removal of the fin cut mask 402 and deposition of an oxide 902between the dummy gates 306 and ends of the substrate 302 exposed by thefin cut. The fin cut mask 402 may be removed using a wet or dry etchselective to other materials that the removal chemistry is exposed to,such as the materials of elements 310, 312 and 316. The oxide 902 may beformed by FCVD deposition following by CMP.

FIGS. 7 and 10-13 show a second process, whereby spacers 312 on only oneside of the dummy gates 306 are preserved. The dummy gates 306 arecompletely removed, and thus there is no gate wrapping around the fin.As shown, the sacrificial layers 308 and 310 used for gate patterningare partially preserved after the fin cut.

FIG. 10 shows a side cross-sectional view 1000 of the FIG. 7 structure,following a nitride open that exposes the dummy gates 306 as shown. Thenitride open may comprise a nitride etch similar to that described abovewith respect to FIG. 8, but with the nitride etch being applied longersuch that all of the sacrificial layer 310 is removed along with aportion of the spacers 312 and poly open CMP layer 314 on the sidewallsof the spacers 312 such that the dummy gates 306 are exposed. Thenitride open, similar to the nitride etch described above with respectto FIG. 8, may be substantially directional such that only a portion ofthe spacers 312 and the poly open CMP layer 314 on the sidewalls of thespacers 312 is removed.

FIG. 11 shows a side cross-sectional view 1100 of the FIG. 10 structurefollowing poly pull and nitride RIE processes, which may be similar tothe nitride and silicon etch processes described above. The particularetch chemistry may vary depending on the type of nitride or othermaterial being etched. The nitride RIE processing is performed first,such that the remaining poly open CMP layer 314 and spacers 312 betweendummy gates 306 is removed. This process may use a directional oranisotropic process that etches materials it is directly exposed to.Since the poly open CMP layer 314 is directly exposed to the RIEchemistry it will etch faster than the spacers 312 where only the top isexposed. Thus, the spacer 312 etches from the top whereas the poly openCMP layer 314 etches from the top and the sides. Following the nitrideRIE, a poly pull process is formed to remove the dummy gates 306. Thepoly pull process, as shown, does not remove the source/drain epitaxiallayer between the dummy gates 306 in some embodiments. This is due tothe chemistry used. For example, various chemistries etch thepolysilicon of the dummy gates 306 much faster than the source/drainepitaxial layer 304, and thus the impact of the poly pull on thesource/drain epitaxial layer 304 between the dummy gates 306 is minimal.

FIG. 12 shows a side cross-sectional view 1200 of the FIG. 11 structurefollowing a silicon etch, similar to the silicon etch described withrespect to FIG. 8, that removes the source/drain epitaxial layer 304between the dummy gates 306 and forms the fin cut in substrate 302.

FIG. 13 shows a side cross-sectional view 1300 of the FIG. 12 structurefollowing removal of the fin cut mask 402 and deposition of an oxide1302 between the spacers 312 and ends of the substrate 302 exposed bythe poly pull and fin cut. The fin cut mask 402 may be removed usingtechniques similar to that described above with respect to FIG. 9. Theoxide 1302 may be formed by FCVD deposition followed by CMP.

FIGS. 14 and 15 depict an alternative embodiment of the second process,wherein additional dry or wet etches are used to remove the gatepatterning hard masks as well as the remaining spacers 312. Removing theremaining portions of the gate patterning hard masks, including theremaining portions of the sacrificial layers 308 and 310 along withremoving the remaining spacers 312 left exposed by removal of the dummygates 306 may provide certain advantages in reducing the parasiticcapacitance of the resulting structure. The extent of this benefit,however, may depend on the layout of the rest of the structure as wellas the materials choices for the spacers 312, poly open CMP layer 314and the eventual dielectric fill used, e.g., the oxide 1502 describedbelow.

FIG. 14 shows a side cross-sectional view 1400 of the FIG. 12 structurefollowing such additional etching, whereby the remaining spacers 312left exposed by removal of the dummy gates 306 are removed along withthe remaining portions of the sacrificial layers 308 and 310 of the gatepatterning hard masks.

FIG. 15 shows a side cross-sectional view 1500 of the FIG. 14 structurefollowing removal of the fin cut mask 402 and deposition of an oxide1502 to fill in the area removed during the fin cut.

Although not explicitly shown in FIGS. 14 and 15, the poly open CMPlayer 314 that surrounding the remaining spacers 312 left exposed byremoval of the dummy gates 306 may also be removed depending on theparticular etch processes and chemistries used.

FIG. 16 depicts a plot 1600 showing in-plane strain data for crystallineorientation 220 in-plane for a SiGe fin. The plot 1600 shows the percentstrain loss percentage in the y-axis as a function of distance innanometers (nm) for device 1602. The plot 1600 shows the percent strainloss, where lower is better, for performing fin cut last as describedabove and also for a conventional technique wherein the fin is cut priorto formation of the FIG. 3 structure described above. The device 1602,as illustrated, has fin cuts at the left and right edges of the bulksilicon substrate. A SiGe gate is formed between spacers and epitaxiallayers. Interlayer dielectric is formed over the epitaxial layers. Theplot 1600 illustrates strain preservation by forming fin cuts later inprocessing as described.

In some embodiments, a method for forming a semiconductor structurecomprises forming a fin cut mask over a region in a finFET structure,where the finFET structure comprises one or more fins and one or moregates and source/drain regions formed over the one or more fins inactive regions of the finFET structure. The method includes performing afin cut by removing a portion of at least one of the fins, the portionof said at least one fin being determined by an exposed area of the fincut mask, the exposed area of the fin cut mask comprising at least aportion of said at least one fin between a first dummy gate and a seconddummy gate formed over said at least one fin. The method also includesremoving the fin cut mask and depositing an oxide to replace the portionof said at least one fin removed during the fin cut.

The fin cut mask, in some embodiments, covers at least a portion of afirst gate structure comprising the first dummy gate and at least aportion of a second gate structure comprising the second dummy gate. Thefin cut mask in such embodiments exposes an area between the first gatestructure and the second gate structure while partially exposing tops ofthe first gate structure and the second gate structure. FIG. 4illustrates an example of such embodiments. In other embodiments, thefin cut mask covers all of the first gate structure comprising the firstdummy gate and all of the second gate structure comprising the seconddummy gate. In such embodiments the fin cut mask exposes an area betweenthe first gate structure and the second gate structure without exposingtops of the first gate structure or the second gate structure. FIG. 5illustrates an example of such embodiments. In still other embodiments,the fin cut mask exposes the first gate structure comprising the firstdummy gate, the second gate structure comprising the second dummy gate,and an area between the first gate structure and the second gatestructure. FIG. 6 illustrates an example of such embodiments.

In some embodiments, such as those illustrated in FIGS. 7-9, the firstdummy gate and the second dummy gate are retained following the fin cut.In other embodiments, such as those illustrated in FIGS. 7 and 10-13,the first dummy gate and the second dummy gate are removed during thefin cut. In such embodiments, portions of a first gate patterning stackformed over the first dummy gate and portions of a second gatepatterning stack formed over the second dummy gate are retainedfollowing the fin cut.

In some embodiments, performing the fin cut comprises etching to removean oxide layer between a first gate structure and a second gatestructure. The first gate structure comprises the first dummy date and afirst gate patterning hard mask structure formed over the first dummygate. The second gate structure comprises the second dummy gate and asecond gate patterning hard mask structure formed over the second dummygate. FIG. 7 illustrates an example of such processing.

As detailed above and as shown in FIGS. 8 and 9, in some embodimentsperforming the fin cut also comprises performing a directional nitrideetch to remove a portion of the first gate patterning hard maskstructure left exposed by the fin cut mask, the portion of the firstgate patterning hard mask comprising a portion of a first sacrificiallayer in the first gate patterning hard mask structure, to remove aportion of the second gate patterning hard mask structure left exposedby the fin cut mask, the portion of the second gate patterning hard maskcomprising a portion of a second sacrificial layer in the second gatepatterning hard mask structure, to remove portions of first spacersformed on sidewalls of the first gate structure and the second gatestructure, and to remove portions of second spacers formed on sidewallsof the first spacers and over an epitaxial layer formed over said atleast one fin between the first gate structure and the second gatestructure. Performing the fin cut may also include performing anepitaxial and silicon etch to remove the epitaxial layer and the portionof said at least one fin between the first gate structure and the secondgate structure. The removed portion of said at least one fin maycomprise portions of said at least one fin not covered by the firstspacers on sidewalls of the first gate structure and the second gatestructure.

As detailed above and as shown in FIGS. 10-13, in some embodimentsperforming the fin cut comprises performing a directional nitride etchto remove a portion of the first gate patterning hard mask structureleft exposed by the fin cut mask, the portion of the first gatepatterning hard mask comprising all of a first sacrificial layer in thefirst gate patterning hard mask structure left exposed by the fin cutmask, to remove a portion of the second gate patterning hard maskstructure left exposed by the fin cut mask, the portion of the secondgate patterning hard mask comprising all of a second sacrificial layerin the second gate patterning hard mask structure left exposed by thefin cut mask, to remove portions of first spacers formed on sidewalls ofthe first gate structure and the second gate structure, and to removeportions of second spacers formed on sidewalls of the first spacers andover an epitaxial layer formed over said at least one fin between thefirst gate structure and the second gate structure. The removed portionsof the first spacers and the second spacers expose at least a portion ofthe first dummy gate and at least a portion of the second dummy gate.Performing the fin cut may further comprise performing a nitridereactive-ion etching to remove the first spacers and the second spacersformed on sidewalls of the first gate structure and sidewalls of thesecond gate structure between the first dummy gate and the second dummygate. Performing the fin cut may further comprise performing a poly pullto remove the first dummy gate and the second dummy gate, and performingan epitaxial and silicon etch to remove the epitaxial layer and theportion of said at least one fin between the remaining first spacersleft exposed by removal of the first dummy gate and the second dummygate.

In some embodiments, a semiconductor structure comprises a finFETstructure comprising one or more fins and one or more gates andsource/drain regions formed over the one or more fins in active regionsof the finFET structure, at least one fin cut between a first gatestructure and a second gate structure formed over at least one of thefins, and an oxide layer formed between adjacent portions of said atleast one fin between the first gate structure and the second gatestructure. The first gate structure comprises a first dummy gate formedover said at least one fin and a first gate patterning mask formed overthe first dummy gate, the second gate structure comprises a second dummygate formed over said at least one fin and a second gate patterning hardmask formed over the second dummy gate, and spacers are formed onsidewalls of the first gate structure and the second gate structure.Notches may be formed in at least a portion of the first gate patterninghard mask, the second gate patterning hard mask and the spacers. In someembodiments, the fin cut may extend in an area over said at least onefin between the first gate structure and the second gate structure butdoes not extend to an area of said at least one fin below the first gatestructure and the second gate structure. The processing described withrespect to FIGS. 7-9 may be used to form such a semiconductor structurein some embodiments.

In some embodiments, a semiconductor structure comprises a finFETstructure comprising one or more fins and one or more gates andsource/drain regions formed over the one or more fins in active regionsof the finFET structure, at least one fin cut between a first gatestructure and a second gate structure formed over at least one of thefins, and an oxide layer formed between adjacent portions of said atleast one fin between a pair of spacers, a first one of the pair ofspacers being part of a first gate structure and a second one of thepair of spacers being part of a second gate structure. The first gatestructure comprises at least a portion of a first gate patterning hardmask formed over a first dummy gate, the first dummy gate being removedwhen performing the fin cut. The second gate structure comprises atleast a portion of a second gate patterning hard mask formed over asecond dummy gate, the second dummy gate being removed when performingthe fin cut. Each of the first gate patterning hard mask and the secondgate patterning hard mask may comprise a first sacrificial layer and asecond sacrificial layer formed over the first sacrificial layer. One ofthe first sacrificial layer and the second sacrificial layer maycomprise a nitride layer and the other one of the first sacrificiallayer and the second sacrificial layer may comprise an oxide layer. Insome embodiments, the fin cut extends in an area of the at least onefine between the first gate structure and the second gate structure aswell as an area of the at least one fin below the first gate structureand the second gate structure. The processing described with respect toFIGS. 7 and 10-13 may be used to form such a semiconductor structure insome embodiments.

In the description above, various materials and dimensions for differentelements are provided. Unless otherwise noted, such materials are givenby way of example only and embodiments are not limited solely to thespecific examples given. Similarly, unless otherwise noted, alldimensions are given by way of example and embodiments are not limitedsolely to the specific dimensions or ranges given.

Semiconductor devices and methods for forming same in accordance withthe above-described techniques can be employed in various applications,hardware, and/or electronic systems. Suitable hardware and systems forimplementing embodiments of the invention may include, but are notlimited to, personal computers, communication networks, electroniccommerce systems, portable communications devices (e.g., cell and smartphones), solid-state media storage devices, functional circuitry, etc.Systems and hardware incorporating the semiconductor devices arecontemplated embodiments of the invention. Given the teachings providedherein, one of ordinary skill in the art will be able to contemplateother implementations and applications of embodiments of the invention.

In some embodiments, the above-described techniques are used inconnection with semiconductor devices that may require, for example,complementary metal-oxide semiconductors (CMOSs),metal-oxide-semiconductor field-effect transistors (MOSFETs), and/orFinFETs. By way of non-limiting example, the semiconductor devices caninclude, but are not limited to CMOS, MOSFET, and FinFET devices, and/orsemiconductor devices that use CMOS, MOSFET, and/or FinFET technology.

Various structures described above may be implemented in integratedcircuits. The resulting integrated circuit chips can be distributed bythe fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A method of forming a semiconductor structure,comprising: forming a fin cut mask over a region in a fin field-effecttransistor (finFET) structure, the finFET structure comprising one ormore fins and one or more gates and source/drain regions formed over theone or more fins in active regions of the finFET structure; performing afin cut by removing a portion of at least one of the fins, the portionof said at least one fin being determined by an exposed area of the fincut mask, the exposed area of the fin cut mask comprising at least aportion of said at least one fin between a first dummy gate and a seconddummy gate formed over said at least one fin; wherein performing the fincut comprises etching to remove an oxide layer between a first gatestructure and a second gate structure, the first gate structurecomprising the first dummy gate and a first gate patterning hard maskstructure formed over the first dummy gate, the second gate structurecomprising the second dummy gate and a second gate patterning hard maskstructure formed over the second dummy gate; and wherein performing thefin cut further comprises performing a directional nitride etch: toremove a portion of the first gate patterning hard mask structure leftexposed by the fin cut mask, the portion of the first gate patterninghard mask comprising a portion of a first sacrificial layer in the firstgate patterning hard mask structure; to remove a portion of the secondgate patterning hard mask structure left exposed by the fin cut mask,the portion of the second gate patterning hard mask comprising a portionof a second sacrificial layer in the second gate patterning hard maskstructure; to remove portions of first spacers formed on sidewalls ofthe first gate structure and the second gate structure; and to removeportions of second spacers formed on sidewalls of the first spacers andover an epitaxial layer formed over said at least one fin between thefirst gate structure and the second gate structure; removing the fin cutmask; and depositing an oxide to replace the portion of said at leastone fin removed during the fin cut.
 2. The method of claim 1, whereinthe fin cut mask covers at least a portion of a first gate structurecomprising the first dummy gate and at least a portion of a second gatestructure comprising the second dummy gate, and wherein the fin cut maskexposes an area between the first gate structure and the second gatestructure.
 3. The method of claim 1, wherein the fin cut mask covers allof a first gate structure comprising the first dummy gate and all of asecond gate structure comprising the second dummy gate, and wherein thefin cut mask exposes an area between the first gate structure and thesecond gate structure.
 4. The method of claim 1, wherein the fin cutmask exposes a first gate structure comprising the first dummy gate, asecond gate structure comprising the second dummy gate, and an areabetween the first gate structure and the second gate structure.
 5. Themethod of claim 1, wherein the first dummy gate and the second dummygate are retained following the fin cut.
 6. The method of claim 1,wherein the first dummy gate and the second dummy gate are removedduring the fin cut, and wherein portions of a first gate patterningstack formed over the first dummy gate and portions of a second gatepatterning stack formed over the second dummy gate are retainedfollowing the fin cut.
 7. The method of claim 1, wherein performing thefin cut further comprises performing an epitaxial and silicon etch toremove the epitaxial layer and the portion of said at least one finbetween the first gate structure and the second gate structure.
 8. Themethod of claim 7, wherein the removed portion of said at least one fincomprises portions of said at least one fin not covered by the firstspacers on sidewalls of the first gate structure and the second gatestructure.
 9. A method of forming a semiconductor structure, comprising:forming a fin cut mask over a region in a fin field-effect transistor(finFET) structure, the finFET structure comprising one or more fins andone or more gates and source/drain regions formed over the one or morefins in active regions of the finFET structure; performing a fin cut byremoving a portion of at least one of the fins, the portion of said atleast one fin being determined by an exposed area of the fin cut mask,the exposed area of the fin cut mask comprising at least a portion ofsaid at least one fin between a first dummy gate and a second dummy gateformed over said at least one fin; wherein performing the fin cutcomprises etching to remove an oxide layer between a first gatestructure and a second gate structure, the first gate structurecomprising the first dummy gate and a first gate patterning hard maskstructure formed over the first dummy gate, the second gate structurecomprising the second dummy gate and a second gate patterning hard maskstructure formed over the second dummy gate; and wherein performing thefin cut comprises performing a directional nitride etch: to remove aportion of the first gate patterning hard mask structure left exposed bythe fin cut mask, the portion of the first gate patterning hard maskcomprising all of a first sacrificial layer in the first gate patterninghard mask structure left exposed by the fin cut mask; to remove aportion of the second gate patterning hard mask structure left exposedby the fin cut mask, the portion of the second gate patterning hard maskcomprising all of a second sacrificial layer in the second gatepatterning hard mask structure left exposed by the fin cut mask; toremove portions of first spacers formed on sidewalls of the first gatestructure and the second gate structure; and to remove portions ofsecond spacers formed on sidewalls of the first spacers and over anepitaxial layer formed over said at least one fin between the first gatestructure and the second gate structure; wherein the removed portions ofthe first spacers and the second spacers expose at least a portion ofthe first dummy gate and at least a portion of the second dummy gate;removing the fin cut mask; and depositing an oxide to replace theportion of said at least one fin removed during the fin cut.
 10. Themethod of claim 9, wherein performing the fin cut further comprisesperforming a nitride reactive-ion etching to remove the first spacersand the second spacers formed on sidewalls of the first gate structureand sidewalls of the second gate structure between the first dummy gateand the second dummy gate.
 11. The method of claim 10, whereinperforming the fin cut further comprises performing a poly pull toremove the first dummy gate and the second dummy gate.
 12. The method ofclaim 11, wherein performing the fin cut further comprises performing anepitaxial and silicon etch to remove the epitaxial layer and the portionof said at least one fin between the remaining first spacers leftexposed by removal of the first dummy gate and the second dummy gate.